Ad hoc communication techniques are communication techniques in which devices perform communications directly with each other without access points. In recent years, the wireless ad hoc network technique, in which each communication device to which an ad hoc communication technique has been applied recognizes communication devices around it, has been gaining attention.
As an example of a routing protocol of an ad hoc network (ad hoc protocol), there is a reactive-type AODV (Ad hoc On-Demand Distance Vector Algorithm) and a proactive-type OLSR (Optimized Link State Routing). As an example of a proactive-type routing protocol, there is a protocol in which each node autonomously establishes a route for performing data communications prior to communication requests and further learns appropriate routes on an as-needed basis so as to change routes.
As an example of a technique related to an ad hoc network, there is a first technique related to a system that performs routing in a multiple-hop wireless communication network including a plurality of network nodes (for example, Patent Document 1). This system includes a unit that obtains quality information representing a link state between the infrastructure and nodes, a unit that uses link quality information in a route determination process in an infrastructure/node that uses prediction procedures, and a routing unit that transmits a data packet through the determined route. Link quality information includes information about a link state that changes temporally. A prediction procedure uses information about a link state that changes temporally in a prediction procedure.
Also, as an example of a communication failure route avoidance technique in a network system, there is a second technique that suppresses packets transmitted from a route selection device (for example, Patent Document 2). According to the second technique, when a destination-inaccessibility report (ICMP message) has been received from an adjacent route selection device that detected the occurrence of a failure in a specified route, the adjacent route selection device performs the following processes. Specifically, the adjacent route selection device switches routing destination adjacent route selection devices and updates a database of a link state corresponding to the network loads, and suppresses transmitted IP packets on the basis of the traffic information in the current adjacent route selection device.
Patent Document 1: Japanese National Publication of International Patent Application No. 2007-529135
Patent Document 2: Japanese Laid-open Patent Publication No. 2002-9820